The present disclosure relates to image forming devices, such as copiers, printers, facsimile machines, multifunction device thereof, etc.
Image forming devices, such as copiers and the like include an exposure unit (exposure device). The exposure unit irradiates laser light to the surface of a photosensitive drum to form an electrostatic latent image. The exposure unit includes a light source that emits laser light, optical components, such as a lens that images the emitted laser light, a polygon mirror that deflects the laser light, etc., a motor that drives and rotates the polygon mirror, and a casing that accommodates them.
The motor (polygon motor) acts as a heat source in the exposure unit. Accordingly, in order to continuously perform stable exposure, it is preferable to dissipate heat generated at the motor outward of the exposure unit to suppress influence of heat storage on the optical components and the like. For example, a heat sink is fixed to the back surface of a base member (substrate), to which the motor is fixed, and is exposed outside of the casing, thereby dissipating the heat of the motor outside of the exposure unit. The heat sink includes, for example, a plurality of fins, which are arrayed in parallel with each other and have the same height. The heat sink is fixed to the base member to generate an air flow from one ends to the other ends of the fins along the fins, thereby enhancing heat dissipation effect.